JP2017211493A - Exposure equipment, exposure method and manufacturing method of article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique advantageous for simultaneously realizing throughput and imaging performance.SOLUTION: Exposure equipment for performing scan exposure of a substrate includes: a projection optical system PO configured to project a pattern of an original plate onto a substrate; and a control part 10. The projection optical system PO includes: a plurality of optical members including a pair of a concave mirror 5 and a convex mirror 6; a plurality of adjustment parts 7 configured to apply a force onto plural locations of a rear face of the concave mirror to adjust a surface shape of the concave mirror 5; and a measurement part 8 configured to measure at least one of a location or a posture of an optical member. The control part 10 is configured to control the plurality of adjustment parts 7 so as to adjust the surface shape of the concave mirror 5 while performing the scan exposure according to a measurement result measured by the measurement part 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exposure apparatus, an exposure method, and an article manufacturing method.

  Liquid crystal display panels have come to be frequently used as display devices such as FPDs (flat panel displays). The liquid crystal display panel is manufactured using a photolithography technique using an exposure apparatus. In recent years, it has become necessary to increase the accuracy of an exposure apparatus, and it has become necessary to correct aberrations of a projection optical system. For example, a technique for correcting aberration by changing the surface shape of a reflecting mirror has been proposed (see Patent Document 1 and Patent Document 2).

JP 2004-056125 A JP 2006-128699 A

  However, the technique of Patent Document 1 is disadvantageous in terms of throughput because it measures the aberration of the projection optical system and determines the surface shape so as to correct the measured aberration. In the technique of Patent Document 2, a deformable reflective device is used for correcting an error caused by non-uniformity of the surface shape of the optical element as a characteristic of the optical system. However, as the resolution of devices increases, even in an exposure apparatus that uses a projection optical system that is well-adjusted with the non-uniformity of the surface shape of the optical element, the displacement of the optical member during exposure It is also necessary to correct the change in optical performance caused by.

  It is an object of the present invention to provide a technique that is advantageous for achieving both throughput and imaging performance.

  According to an aspect of the present invention, there is provided an exposure apparatus that performs scanning exposure of a substrate, and includes a projection optical system that projects an original pattern onto the substrate, and a control unit, and the projection optical system includes a pair of projection optical systems. At least one of a plurality of optical members including a concave mirror and a convex mirror, a plurality of adjustment units that apply force to a plurality of locations on the back surface of the concave mirror in order to adjust the surface shape of the concave mirror, and the position and posture of the optical member The control unit controls the plurality of adjustment units to adjust the surface shape of the concave mirror during the execution of the scanning exposure based on the measurement result measured by the measurement unit. An exposure apparatus characterized in that is provided.

  According to the present invention, a technique advantageous in achieving both throughput and imaging performance is provided.

1 is a schematic block diagram of an exposure apparatus in an embodiment. The figure which shows the example of the shape of the slit which embodiment illumination optical system has. The figure which shows the example of the pattern on a mask. The figure which shows the example of the pattern on a mask. The figure which shows the example of a characteristic of astigmatism. The flowchart of the correction process of the concave mirror in embodiment. The figure which shows the example of the support structure of a convex mirror.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, The following embodiment shows only the specific example of implementation of this invention. Moreover, not all combinations of features described in the following embodiments are indispensable for solving the problems of the present invention.

  FIG. 1 is a schematic block diagram of an exposure apparatus in the embodiment. The exposure apparatus of this embodiment includes an illumination optical system IL. The illumination optical system IL includes a light source, and it is possible to select an optimal light source for a device manufactured from an excimer laser, a high-pressure mercury lamp, or the like. For example, g-line (436 nm), h-line (405 nm), and i-line (365 nm) can be used for manufacturing a liquid crystal display element using a high-pressure mercury lamp.

  For example, a circuit pattern necessary for manufacturing a liquid crystal display element is drawn on the mask 1 which is an original. The mask 1 is mounted on the mask stage 2. The mask 1 is irradiated with exposure light from the illumination optical system IL. The exposure light transmitted through the mask 1 passes through the projection optical system PO and forms an image of the mask 1 on the substrate 3.

  The substrate 3 is mounted on the substrate stage 4, and a large area can be exposed by scanning the mask stage 2 and the substrate stage 4 in synchronization. The substrate 3 is coated with a photosensitive material sensitive to exposure light, and a pattern can be formed on the substrate through a development process. Projection optical system PO includes a pair of concave mirror 5 and convex mirror 6. The exposure light emitted from the mask 1 is reflected by the concave mirror 5, reflected by the convex mirror 6, and again reflected by the concave mirror 5, and an image of the mask 1 is formed on the substrate 3. The projection optical system PO may also include a refractive member 9 that refracts exposure light in order to correct aberrations. The refracting member 9 includes, for example, a parallel plate. By tilting the parallel plate with respect to the optical axis, coma aberration, astigmatism, and distortion can be corrected. The concave mirror 5 may be integrated or divided.

  In the projection optical system PO including the concave mirror 5 and the convex mirror 6 shown in FIG. 1, an off-axis arcuate good image area can be used for exposure. The illumination optical system IL includes a slit 11 having an arcuate opening as shown in FIG. 2 in order to illuminate the arcuate good image area.

  As the coordinate system of this exposure apparatus, the Z axis is taken in the direction from the substrate 3 toward the mask 1, the Y axis is taken in the direction from the convex mirror 6 toward the concave mirror 5, and the X axis is taken to form a right hand system. Also, ωx is taken in the rotational direction in which the right screw advances in the positive direction around the X axis. ωy and ωz are similarly defined around the Y axis and the Z axis, respectively.

  The projection optical system PO includes a plurality of adjustment units 7 (drive mechanisms) that apply force to a plurality of locations on the back surface of the concave mirror in order to adjust the surface shape of the concave mirror 5. For the adjusting unit 7, an arbitrary element such as a piezoelectric element can be used. It is possible to change the shape of the reflecting surface of the concave mirror 5 by driving the plurality of adjusting units 7. When the surface shape is deformed, the optical performance of the projection optical system PO changes according to the shape. Accordingly, it is possible to control the optical performance of the projection optical system PO by controlling the plurality of adjusting units 7.

  The projection optical system PO includes a measuring unit 8 for measuring at least one of the position and posture of the convex mirror 6. The measuring unit 8 can be constituted by a length measuring machine using a laser, for example. The length measuring machine can measure at least one of the position (X, Y, Z) and the posture (ωx, ωy, ωz) by selecting an optimal arrangement and number. The measurement unit 8 shown in FIG. 1 measures the position and orientation of the convex mirror 6, but the optical member to be measured is a convex mirror 6, a plurality of optical members including the concave mirror 5 and the refractive member 9. It may be at least one of them. Moreover, it is also possible to measure the position and orientation of a plurality of optical members simultaneously by using a plurality of measuring units.

  The measuring unit 8 is connected to the control unit 10. The control unit 10 can obtain a measurement result from the measurement unit 8 and predict a change in optical performance corresponding to a change in the position and orientation of the convex mirror 6 (hereinafter also simply referred to as “displacement”). The optical performance may include spherical aberration, curvature of field, astigmatism, coma aberration, distortion, uniform displacement of the imaging position in the X and Y planes, and the like.

  3 and 4 show examples of patterns on the mask 1. As shown in FIG. 3, a pattern long in the X direction is called an H pattern, and a pattern long in the Y direction as shown in FIG. 4 is called a V pattern. When astigmatism is present in the projection optical system PO, a difference occurs in the image forming position (focus position) in the Z direction between the H pattern and the V pattern. Due to the presence of astigmatism, a difference occurs between the focus positions of the H pattern and the V pattern, and the imaging performance deteriorates.

  Each optical member in the projection optical system PO may deviate from its original position and orientation due to the influence of disturbance from the floor on which the exposure apparatus is installed. For example, as shown in FIG. 7, the convex mirror 6 is held by a holder 61, and the holder 61 is fixed by a fixing member 63 via a shaft 62 that is a rod-shaped member extending in the lateral direction (X-axis direction). It is being fixed to the inner wall of the chamber C which comprises a housing | casing. The direction in which the shaft 62 extends may be the vertical direction (Z-axis direction). Alternatively, the holder 61 may be fixed by a plurality of shafts extending in the horizontal direction and the vertical direction (and in other directions). In order for the convex mirror 6 not to be affected by disturbance during scanning exposure, the support rigidity of the convex mirror 6 is required to be sufficiently high. However, since the periphery of the convex mirror 6 is an optical path for exposure light, it is necessary to keep the optical path from being blocked by the shaft 62 to a minimum. For this reason, there is a limit to increasing the rigidity of the shaft 62, and the position and orientation of the convex mirror 6 among the optical members in the projection optical system PO are likely to be shifted due to the influence of disturbance during scanning exposure. Further, when the position and orientation of the convex mirror 6 is deviated, it is only necessary to restore the position and orientation of the convex mirror 6 itself, but it is difficult to arrange such a mechanism so as not to disturb the optical path of the exposure light. is there. Therefore, in the present embodiment, as described below, for example, the surface shape of the concave mirror 5 is changed by controlling the plurality of adjusting units 7 so as to correct the change in the optical characteristics accompanying the change in the position and orientation of the convex mirror 6. It was decided.

  When the optical member such as the convex mirror 6 is deviated from the original position and orientation, the imaging performance is changed according to the deviation amount. For example, FIG. 5 is a graph showing the difference between the image forming position (focus position) of the H pattern and the V pattern when the convex mirror 6 changes in the Y direction. The horizontal axis in FIG. 5 represents the position of the slit in the X direction in FIG. 2, and the vertical axis represents the difference in focus position between the H pattern and the V pattern (astigmatism amount). In the present embodiment, the amount of change in astigmatism with respect to the change in the Y direction of the convex mirror 6 is shown. However, the displacement in the X direction and the Z direction, the postures ωx, ωy, ωz of the optical member and other aberrations are arbitrary. Combinations are possible.

  In the embodiment, the prediction of the amount of astigmatism generated with respect to the displacement of the convex mirror 6 is performed as follows, for example. The amount of astigmatism generated with respect to the displacement is obtained in advance by optical simulation. The correspondence between this displacement and the amount of astigmatism generated is held in a memory in the control unit 10 as a reference table, for example. Then, based on this correspondence, the control unit 10 can predict the amount of astigmatism generated corresponding to the measurement result of the measuring unit 8 as the amount of astigmatism generated in the projection optical system PO. it can. Alternatively, it is also possible to measure the displacement of the convex mirror 6 by the measurement unit 8 and perform an optical simulation based on the measurement result to calculate the amount of astigmatism.

  Next, the control unit 10 determines the surface shape of the concave mirror 5 for correcting the predicted aberration. In the present embodiment, astigmatism correction is taken as an example, but it is possible to calculate a surface shape that takes into account arbitrary aberrations such as the above-mentioned coma and distortion. It is also possible to calculate a surface shape for correcting a plurality of aberrations. In order to deform the surface shape of the concave mirror 5 with the surface shape for correcting the calculated aberration as a target, the control unit 10 calculates the drive amount of each of the plurality of adjustment units 7. The control unit 10 drives each adjustment unit with the calculated drive amount. Thereby, the surface shape of the concave mirror 5 is deformed to a desired surface shape, and astigmatism accompanying the displacement of the convex mirror 6 can be corrected.

  The above correction can be performed as follows, for example. First, during step driving of the substrate stage 4 that is not being exposed or during exchange of the substrate, the control unit 10 obtains the displacement of the convex mirror 6 based on the measurement result of the measurement unit 8 and predicts the aberration caused by the displacement. . Thereafter, the control unit 10 determines the surface shape of the concave mirror 5 for correcting the aberration, and drives the plurality of adjusting units 7 to correct the aberration of the projection optical system PO.

  In the above, astigmatism correction when the convex mirror 6 is changed in the Y direction has been described as a specific example. As another example, when the posture of the convex mirror 6 is changed to + ωx, the imaging position is changed in the + Y direction as a whole. For example, when the convex mirror 6 vibrates in the ± ωx direction due to disturbance during scanning exposure, the imaging position on the substrate 3 vibrates in the ± Y direction. When the imaging position is vibrated during the scanning exposure, the contrast of the image is lowered and the imaging performance is lowered. For the correction, the posture ωx of the convex mirror 6 is always measured during exposure, and the control unit 10 predicts the change in the imaging position due to the change in the posture ωx. Based on the prediction, the surface shape of the concave mirror 5 for correcting the deviation of the imaging position is calculated, and the surface shape of the concave mirror 5 is deformed by driving the plurality of adjusting units 7 with the calculated surface shape as a target. . By performing these processes in real time, the vibration of the image on the substrate 3 can be suppressed. As a result, it is possible to prevent a decrease in contrast and obtain good imaging performance.

  The above-described measurement by the measurement unit 8, prediction of imaging performance (aberration), calculation of the surface shape of the concave mirror, and driving of the plurality of adjustment units are performed not only during scanning exposure but also during non-execution of scanning exposure. It can be implemented at any timing. Further, as described above, not only the change in aberration but also the displacement of the imaging position in the X and Y planes is effective.

  In the present embodiment, the displacement of the convex mirror 6 has been described. However, for example, by providing a measuring unit that measures the displacement of the concave mirror 5 provided with the refracting member 9 and the driving mechanism, it is caused by the displacement and posture change of the refractive member 9 and the concave mirror 5. Changes in imaging performance can be corrected in a similar manner. In addition, the displacement of the plurality of optical members of the convex mirror 6, the refractive member 9, and the concave mirror 5 is measured, and it is predicted how the imaging performance of the projection optical system PO changes due to the displacement of the plurality of optical members. Is possible. The surface shape of the concave mirror 5 for collectively correcting the change in the imaging performance predicted by the displacement of the plurality of optical members is calculated, and the driving amounts of the plurality of adjusting units 7 are calculated from the calculated results. The adjusting unit 7 may be driven. Thereby, the change of the optical performance which generate | occur | produced with the some optical member can be correct | amended. As described above, the optical member to be measured and the aberration for predicting the direction and change of the displacement can be arbitrarily selected and combined.

  FIG. 6 is a flowchart of the correction process of the concave mirror 5 by the control unit 10. First, the control unit 10 measures the positions X, Y, Z and postures ωx, ωy, ωz of optical members included in the projection optical system PO based on the measurement data acquired from the measurement unit 8 (S1). Next, the control unit 10 predicts a change in optical performance (aberration) from the measured change in position and orientation (S2). Based on the predicted change in optical performance, the controller 10 calculates the surface shape of the concave mirror 5 that corrects the change in optical performance (S3). Next, the control unit 10 calculates the drive amount of each of the plurality of adjustment units 7 with the calculated surface shape as a target (S4). And the control part 10 drives the some adjustment part 7 according to the calculated drive amount (S5). As described above, this correction processing can be performed during execution of scanning exposure. The correction process may be performed while scanning exposure is not being performed, as well as when scanning exposure is being performed.

  Next, a modified example of the above-described embodiment will be described. The deformation of the substrate can be measured before exposure, and the drive mechanism is driven based on the measurement result before exposure, and the influence on the imaging performance due to the deformation of the substrate can be corrected. However, the optical members included in the projection optical system are constantly oscillating due to disturbances, etc., and the position of the optical member is measured before exposure, the aberration is predicted from the result, and the drive mechanism is driven to drive the optical performance. It is difficult to correct this. In the correction of the imaging performance, for example, information on the position of the optical member to be measured is fed back to the control unit 10 and the plurality of adjustment units 7 are controlled. Depending on the scanning speed and the vibration speed, the plurality of adjustment units 7 are controlled. In some cases, sufficient time cannot be taken for feedback control.

  In the case of an exposure apparatus that performs scanning exposure, an average value of the performance change of the projection optical system PO appears as a change in imaging performance while one point on the mask 1 passes under the exposure light irradiated from the slit 11. Therefore, it is possible to correct the exposure result without correcting all aberration changes during exposure. For example, the control unit 10 acquires measurement results at each measurement point in the measurement unit 8 while one point of the mask 1 passes through a predetermined portion (for example, a half region) of the exposure region by scanning exposure. The control unit 10 calculates an average value of the acquired measurement values, predicts a change in aberration from the average value, and calculates a surface shape of the concave mirror that corrects the predicted change in aberration. Then, the control unit 10 sets a plurality of adjustment units with the calculated surface shape as a target while one point of the mask 1 passes through the remaining part (the remaining half) of the exposure area except the predetermined part by the scanning exposure. Each adjustment unit is controlled to drive 7. Thereby, for example, correction of the aberration change in the first half is performed, and it is possible to suppress a decrease in imaging performance. In the above example, the average value of the positions when passing through the exposure region half is taken as an example, but an optimal amount may be calculated from the time required for driving and the correction accuracy.

<Embodiment of Method for Manufacturing Article>
The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. In the method for manufacturing an article according to the present embodiment, a latent image pattern is formed on the photosensitive agent applied to the substrate using the above-described exposure apparatus (a step of exposing the substrate), and the latent image pattern is formed in this step. Developing the substrate. Further, the manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

IL: illumination optical system, PO: projection optical system, 1: mask (original), 2: mask stage, 3: substrate, 4: substrate stage, 5: concave mirror, 6: convex mirror, 7: adjustment unit, 8: measurement unit , 9: refractive member, 10: control unit

Claims (10)

An exposure apparatus that performs scanning exposure of a substrate,
A projection optical system for projecting an original pattern onto the substrate;
A control unit;
Have
The projection optical system is
A plurality of optical members including a pair of concave mirrors and convex mirrors;
A plurality of adjusting portions for applying a force to a plurality of locations on the back surface of the concave mirror in order to adjust the surface shape of the concave mirror;
A measurement unit that measures at least one of the position and orientation of the optical member;
Including
The control unit controls the plurality of adjustment units so as to adjust the surface shape of the concave mirror during the execution of the scanning exposure based on the measurement result measured by the measurement unit. .   The exposure apparatus according to claim 1, wherein the measurement unit measures at least one of a position and a posture of the convex mirror.   The exposure apparatus according to claim 1, wherein the convex mirror is fixed to an inner wall of a housing of the projection optical system via a rod-shaped member. The controller is
Aberration is predicted based on the measurement result of the measurement unit,
Calculating a surface shape of the concave mirror for correcting the predicted aberration;
The exposure apparatus according to any one of claims 1 to 3, wherein the plurality of adjustment units are controlled with the calculated surface shape as a target.   The exposure apparatus according to claim 4, wherein the control unit predicts the aberration from a correspondence relationship between a displacement of the optical member that is a measurement target of the measurement unit and aberration, which is obtained in advance.   The exposure apparatus according to claim 1, wherein the control unit further controls the plurality of adjustment units even when the scanning exposure is not performed.   The exposure apparatus according to claim 1, wherein the plurality of optical members include a refraction member that refracts exposure light to correct aberrations.   The exposure apparatus according to claim 7, wherein the measurement unit measures at least one of a position and a posture of the refractive member. The measurement unit performs measurement while one point of the original passes through a predetermined part of an exposure area by the scanning exposure,
The controller is
Aberration is predicted based on the result of the measurement,
Calculating the surface shape of the concave mirror that corrects the predicted aberration;
2. The plurality of adjustment units are controlled with the calculated surface shape as a target while the one point passes through the remaining portion excluding the predetermined portion of the exposure region by the scanning exposure. 8. The exposure apparatus according to any one of items 7 to 7. A step of exposing a substrate using the exposure apparatus according to claim 1;
Developing the substrate exposed in the step;
A method for producing an article comprising:

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